Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Using dynamic method and the laser monitoring observation technique, the solubility of cefodizime disodium in water + (ethanol, 1-propanol, and 2-propanol) was measured as a function of temperature from 278.15 K to 318.15 K under atmospheric pressure. The experimental data were correlated with a simple model of molecular thermodynamics for solubility of solid in liquid. The model parameters were fitted, and the solution enthalpies and solution entropies were estimated. Solution enthalpies and solution entropies are all positive. The endothermic effect of solution process may be due to the fact that the newly bond energy between cefodizime disodium and solvent molecules is not powerful enough to compensate the energy needed to break the original association bond in various solvents, and the system needs to absorb heat from surroundings and manifests as solution enthalpy greater than 0. The reason for the entropy increase during the dissolution process is that the solutes disrupt the alignment of solvent molecules and therefore reduced the degree of order of the system while they were dissolved in various solvents. The positive solution enthalpy and solution entropy revealed that the dissolution process of cefodizime disodium was an entropy-driven process.